private_recommendations_utils/dgk_comparison_client.cpp

Go to the documentation of this file.

/*
SeComLib
Copyright 2012-2013 TU Delft, Information Security & Privacy Lab (http://isplab.tudelft.nl/)

Contributors:
Inald Lagendijk (R.L.Lagendijk@TUDelft.nl)
Mihai Todor (todormihai@gmail.com)
Thijs Veugen (P.J.M.Veugen@tudelft.nl)
Zekeriya Erkin (z.erkin@tudelft.nl)

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
#include "dgk_comparison_client.h"
//avoid circular includes
#include "dgk_comparison_server.h"

namespace SeComLib {
namespace PrivateRecommendationsUtils {
    DgkComparisonClient::DgkComparisonClient (const Paillier &paillierCryptoProvider, const Dgk &dgkCryptoProvider) :
        paillierCryptoProvider(paillierCryptoProvider),
        dgkCryptoProvider(dgkCryptoProvider) {
    }

    void DgkComparisonClient::SetZModTwoPowL (const BigInteger &zModTwoPowL) {
        this->b = zModTwoPowL;
    }

    Dgk::Ciphertext DgkComparisonClient::GetTb (const Dgk::Ciphertext &tau, const size_t i) const {
        Dgk::Ciphertext tb;

        if (this->b.GetBit(i) == 0) {
            tb = this->dgkCryptoProvider.GetEncryptedZero(false);
        }
        else {
            // @f$ \llbracket tb \rrbracket = \llbracket \tau \rrbracket @f$
            tb = tau;
        }

        tb = this->dgkCryptoProvider.RandomizeCiphertext(tb);

        return tb;
    }

    Dgk::Ciphertext DgkComparisonClient::GetBi (const size_t i) const {
        return this->dgkCryptoProvider.EncryptInteger(BigInteger(static_cast<long>(this->b.GetBit(i))));
    }

    Paillier::Ciphertext DgkComparisonClient::ConvertToPaillier (const Dgk::Ciphertext &dgkCiphertext) const {
        if (this->dgkCryptoProvider.IsEncryptedZero(dgkCiphertext)) {
            return this->paillierCryptoProvider.GetEncryptedZero();
        }
        else {
            return this->paillierCryptoProvider.GetEncryptedOne();
        }
    }

    Paillier::Ciphertext DgkComparisonClient::ComputeDiPSP (const Dgk::Ciphertext &CiPSP) const {
        int decryptedCiPSP;
        if (this->dgkCryptoProvider.IsEncryptedZero(CiPSP)) {
            decryptedCiPSP = 0;
        }
        else {
            decryptedCiPSP = 1;
        }

        int diPSP = this->b.GetBit(this->dgkComparisonServer->GetMSBPosition()) ^ decryptedCiPSP;

        if (diPSP == 0) {
            return this->paillierCryptoProvider.GetEncryptedZero();
        }
        else {
            return this->paillierCryptoProvider.GetEncryptedOne();
        }
    }

    void DgkComparisonClient::SetServer (const std::shared_ptr<DgkComparisonServer> &dgkComparisonServer) {
        this->dgkComparisonServer = dgkComparisonServer;
    }

    void DgkComparisonClient::DebugDgkEncryption (const Dgk::Ciphertext &input) const {
        std::cout << !this->dgkCryptoProvider.IsEncryptedZero(input) << std::endl;
    }

}//namespace PrivateRecommendationsUtils
}//namespace SeComLib